1. Field of the Invention
The present invention relates generally to wheelchair accessories and, more particularly, to an anti-tip wheelchair attachment which, when engaged, renders an occupied wheelchair incapable of tipping over or of propulsion by its main wheels. The invention, therefore, may be defined Properly as a wheelchair stabilizer.
2. Description of the Prior Art
Wheelchair usage, regardless of the specific purpose, normally envisions some form of attendance to the occupant. In situations where the occupant need not be attended, the instant invention, although it may be attached to the lower frame of the wheelchair, would provide no benefit and, in all probability, its engagement would appear senseless. However, in the many instances when a wheelchair occupant must be attended, the instant invention most surely should be used because an attendant is often distracted or called away from the immediate vicinity of the occupied wheelchair. There are numerous instances on record wherein wheelchair occupants have either inadvertently, or intentionally, tipped over the chair. Most often this is done by thrusting the upper torso backward so that the center of gravity of the occupant-chair passes well aft of and over the chair's main wheel axis. In cases involving an agitated patient, most often a mental patient, it is known that violent side-to-side movements by the occupant have readily tipped conventional wheel chairs. The instant inventor, engaged in constructing wheelchair accessories, herein discloses a device which will allow a wheelchair occupant to be left unattended for short periods, so that the chair itself will be rendered immobile and virtually nontippable. Thus, it is to prior art that discloses restraining devices, anti-tip devices or tilting and nontilting apparatus that the reader's attention is now drawn.
In U.S. Pat. No. 2,521,330, issued in September 1950, A. H. Berra et al. disclosed a SLED RUNNER ATTACHMENT FOR BABY BUGGIES. The attachment of Berra is inwardly rigged, that is, attached to the lower frame of the buggy inward of the main wheels. Unique in this invention is the adaptation of an articulable quadrilateral frame of which the sled runner comprises one side. When the frame, bearing the runner, is moved from its folded parallelogram shape to the extended full rectangular shape, the runner engages the ground and, the rectangular sides being longer than the distance from the main wheel axis to the ground, lift the wheels of the buggy off the ground. Thus, Berra discloses a movable apparatus which uniformly and simultaneously lifts all wheels of the vehicle from off the ground, providing it with greater mobility over the particular medium (ice or snow) on which it glides.
Constantin, in U.S. Pat. No. 4,690,364, issued September 1987 discloses a mechanism for locking a wheelchair in a moving vehicle and is entitled WHEELCHAIR RESTRAINING DEVICE. Notably in this invention, the inventor employs a framework comprised of a pair of parallel bars, joined one to the other in an "H" configuration, and having at the ends thereof telescoping, adjustable clamp members for engaging the lower frame elements of a wheelchair. Once the Constantin invention is bolted to the frame of the chair, inward of the main wheels, it is then disposed over and brought into contact registry with the mounting plate assembly that has been secured to the floor of a vehicle, such as a van. Thereafter, the invention's "H" frame engages the van assembly and the wheelchair is restrained in the position where the mechanism is engaged. The invention affords constraint of the chair so that it cannot easily tilt; indeed even a modest accident will not disjar the chair from the Constantin device. It nonetheless cannot be used readily in the vast majority of cases where wheelchairs are employed. Generally, a wheelchair is employed in a environment that allows most of the occupants, whether attended, to move about freely. In the cases of the attended patients, to employ a device such as that taught by Constantin would require myriad emplacements of the (van anchoring) apparatus about hospitals, health care facilities and nursing home grounds. Thus, although this invention has a high degree of specialized usage, its general employment is impractical. What is especially noteworthy about the Constantin disclosure, however, is the fact that the inwardly rigged apparatus, because of its constraint to the ground (floor of the van), is remarkably stable. After a diligent search of the prior art, the applicant concluded that there is no existence of an inwardly rigged wheelchair constraint or stabilizer, other than that art disclosed by Constantin, that would afford the safety and security of the applicant's invention.
Lastly, U.S. Pat. No. 4,565,885, issued to Morford in Jan. 1986, discloses a tiltable supporting wheelchair having a tilting mechanism with front support wheels that pivot downward, outwardly engaging the floor (or ground) and which raise the front of the wheelchair so as to tilt it backwards, This mechanism includes a cross-frame pivotably attached to the frame of the wheelchair and actuated by movement of a lever-linked arm which is attached to it. Contrary to the instant applicant's invention, the Morford device does not stabilize the wheelchair, but rather tilts it back slightly. This retains full mobility of the chair but is done in order to grant relief (from traditional upright sitting positions) to a patient who must reside in the chair for extended periods.
There continues to exist, in the wheelchair art, a need for an easily attachable, readily removable apparatus that will allow a wheelchair attendant to alone immobilize an occupied wheelchair in a position of absolute stability so as to insure that, regardless of the body motions of the occupant, the chair cannot be made to tip over by the occupant.